1. Technical Field
Several aspects of the present invention relate to a droplet discharging head and a droplet discharging device.
2. Related Art
A droplet discharging device, for example, such as an inkjet printer is provided with a droplet discharging head for discharging a droplet.
As such a droplet discharging head, for example, a head including ink chambers, which are communicated with nozzles and contain ink, and piezoelectric elements, which drives deforming wall surfaces of the ink chambers, has been known (see JP-A-5-318727, an example of related art).
In a droplet discharging head of the related art example, a part of a wall surface of an ink chamber serves as a vibration plate.
To the vibration plate is bonded the above-mentioned piezoelectric element, and around the vibration plate is bonded an auxiliary piezoelectric element.
The main piezoelectric element and the auxiliary piezoelectric element each have a piezoelectric material layer with piezoelectricity and a pair of electrode layers sandwiching the piezoelectric material layer, and expand and contract in the thickness direction of the vibration plate.
Particularly, in the related art example, the polarization direction of the piezoelectric material layer in the main piezoelectric element is the same as that of the piezoelectric material layer in the auxiliary piezoelectric element.
The main piezoelectric element and the auxiliary piezoelectric element are linked to each other on the side remote from the ink chamber.
In the foregoing droplet discharging head, part (vibration plate) of the ink chamber is displaced by expansion and contraction of the main piezoelectric element.
This causes alteration of the volume of the ink chamber, allowing ink droplets to be discharged from a nozzle.
At that point, when the main piezoelectric element expands the auxiliary piezoelectric element contracts, whereas when the main piezoelectric element contracts, the auxiliary piezoelectric element expands.
Thus, stiffness of partition walls of the ink chamber is enhanced and the driving power from the main piezoelectric element to the vibration plate is efficiently transmitted, allowing the displacement amount of the vibration plate to be increased.
As a result, electric power of the droplet discharging head can be saved.
However, in the droplet discharging head according to the related art example, since the polarization direction of the piezoelectric material layer in the main piezoelectric element is the same as that of the piezoelectric material layer in the auxiliary piezoelectric element.
This may lead to increasing the cost of the droplet discharging head in driving the main piezoelectric element and the auxiliary piezoelectric element as described above.
Specifically, wiring between the main piezoelectric element or the auxiliary piezoelectric element and a driving circuit may become complicated, and individual driving signals (voltages) for driving the main piezoelectric element and the auxiliary piezoelectric element may become required, making the driving circuit complicated.